-er c-- ccc cce ccf ccg cco ccr ccs ce- cec cee cef ceg ceo cer ces cfc cfe cff cfg cfo cfr cfs cgc cge cgg cgo cgr cgs co- coc coe cof cog coo cor cos crc cre crf crg cro crr crs csc cse csf csg cso csr css ec- ecc ece ecf ecg eco ecr ecs eec eee eef eeg eeo eer ees ef- efc efe eff efg efo efr efs egc ege egf egg ego egr egs eo- eoc eoe eof eog eoo eor eos erc ere erf erg ero err ers es- esc ese esf esg eso esr ess fcc fce fcf fcg fco fcr fcs fec fee fef feg feo fer fes ffc ffe fff ffg ffo ffr ffs fgc fge fgf fgg fgr fgs foc foe fof fog foo for fos frc fre frf frg fro frr frs fsc fse fsf fsg fso fsr fss gcc gce gcf gcg gco gcr gcs ge- gec gee gef geg geo ger ges gfc gfe gff gfo gfr gfs ggc ggg ggo ggr ggs goc goe gof gog goo gor gos grc gre grf grg gro grr grs gsc gse gsf gsg gso gsr gss oc- occ ocf ocg oco ocr ocs oec oee oef oeg oeo oer oes of- ofc ofe off ofg ofo ofr ofs ogc oge ogf ogg ogo ogs oo- ooc oof oog ooo oor oos or- orc ore orf org oro orr ors os- osc ose osf osg oso osr oss rcc rce rcf rcg rco rcr rcs re- rec ree ref reg reo rer res rfc rfe rff rfg rfo rfr rfs rgc rge rgf rgg rgo rgr rgs roc roe rof rog roo ror ros rrc rrf rrg rrr rrs rsc rse rsf rsg rso rsr rss scc sce scf scg sco scr scs se- sec see sef seg seo ser ses sfc sfe sff sfg sfo sfr sfs sgc sge sgf sgg sgo sgr sgs soc soe sof sog soo sor sos sr- src sre srf srg sro srr srs ss- ssc sse ssf ssg sso ssr sss